opticalbeamformingnetworks in selex si - escies

Photonic Technologies for SpacebornBeam Forming Networks

Optical Beam Forming Networksin Selex SILuigi Pierno

ESA- ESTEC 21° November 2008

ESA ESTEC 21° November 2008

Outline

Architectures for Optical BFN and routing for M-AESA

COTS and critical optical components for OBFN

R&D activities in Selex SI

Conclusion


OBFN advantages in antenna

Advantages of OBFN in Terrestrial, Naval, Airborne and Spaceborn M-AESA antennas

•Low weight , size , EMC typical of fiber optics

•True Time Delay (squint free) approach

•Wide bandwidth (>30 GHz ) of optical analogue or digitaltransmission (for Multi Role Antenna)

•Smart Antenna (dynamic routing among functions, low loss remotingof components)

•Optical Beamforming architecture applies to analogue and digitalradar front end (Digital MF Radar)


Architectures for OBFN: Wavelength Domain Multiplexing

MWL

1 2,…. N

Mod

AWG

N

21

Sub Array

(a)

AOTFPD

Sub Array

(b)

AOTFPD

Sub Array(M)

AOTFPD

1 2,…. N

1 2,…. N

a ( a )

b ( b )

M ( M )

PD

Mod

PD

Mod

PD

Mod

PD

AWG

21

Wavelength Fiber Optic Delay

Based on ElectroOptical or AcoustoOptical Tunable Filters


TTD

TTD

TTD

TTD

TTD

Splitting NetworkSystem on a chip

40:10

OA

1x10

RF Input (2)Switch Matrix 4x 1

Switch Matrix 4x 1

Switch Matrix 4x 1

Switch Matrix 4x 1

Switch Matrix 4x 1

Opt. Source

RF Input (1)

1x10

RF Input (3)

1x10

Opt. Source

Opt. Source

1x10

RF Input (4)

Opt. Source

Architectures for OBFN: Time Domain Multiplexing for COSMO like antenna

TDM Architecture for multifunctional COSMO likeantenna (Transmit mode)

Ref: 28th Antenna Workshop on Space Antenna Systems and TechnologiesDIGITAL OPTICAL SWITCHES IN TTD FOR SPACE ACTIVE ANTENNASMauro Varasi, Luigi Pierno, Massimiliano Dispenza, Roberta Buttiglione, Fulvia Verzegnassi


OBFN advantages in COSMO like antenna

60 dBOptical Crosstalk (single TTD)

NegligibleOptical Extinction

30dBCross Talk Extinction

<10gMass

1mWPower consumtion

12 x 12 x 2 cm3Volume

18dBOptical Losses

< 10 nsecRec. speed

5 bits(0,47 = 1 bit)

N° of bits

15 TTD required

40TTD modules

Proposed TTDParameter HighSpeed of reconfigurability of Optical Beam Forming Network due to the Electrooptical drive of the devices

High degree of integration Suitalblefor satellite payload

Nc

zStep

2z H sin

ANTENNA DIVIDER

1:8 div.

1:4 div. Tile Divider

TDL

ANTENNA DIVIDER

1:8 div.

1:4 div. Tile Divider

1:3 div.

Panel Divider

1:2 div.

CALIBRATION NETWORK

efe

T/R MODULESEFEDIVIDER

DISTRIBUTION NETWORK

1:3 div.

Panel Divider

1:2 div. 1:2 div. 1:2 div.


OBFN2OBFN1

Beam 2 Beam 4Beam 1 Beam 3optical source

Wideband LNA

Opticalmodulator

Antenna array

8 fibre SM ribbon cable(10 metre)

Apodising Filters

RF Combiner

1 2 8 9 16

16 fibre PM ribbon cable(10 metre)

Beam outputs

Wing-Mounted Sub-Module

Fuselage Sub-Module

Lasers

Demonstrator Architecture for Receive operation

DOS Fine Time Delay Trimming modules

Architectures for OBFN: EWOCS(*) project

(*) EDA project in partnership with BAE Systems


Fuselage Module & Wing-Mounted Module

Photonics components for OBFN: EWOCS

Based on Selex SI Modulators


6-18GHz frequency coverage4GHz instantaneous bandwidth16 antenna elements (in a linear array)Angular coverage/TTD array: ±45o azimuth, ±45o elevation Adjacent beam crossover: 3 - 8 dB below beam peakNext adjacent beam crossover = 20 dB below beam peak and greater than the

highest sidelobe

-30dBm Maximum Signal

Maximum noise level

20dB MinimumSignal-to-third orderIntermodulationProduct

-50dBmMaximum Third OrderIntermodulation Product

45dB DynamicRange

-75dBm MinimumDetectable RF Signal

6dB MinimumSignal-to-NoiseRatio

Performance of OBFN: EWOCS project


MORSE (*) Project Objectives

Multifunctional Antenna (S&T, Comms, Synthetic Aperture Radar for Imaging, ….)

Dynamical Reconfigurability of the apertureWide bandwidthLinearity - Dynamic rangeScalabilityReliability

Optical Routing and Beamforming Architecture

Radar Rx

EW Rx

Comms Rx

Comms Rx

Op

tica

lMIR

Op

tica

lMIR

Op

tica

lMIR

Op

tica

lMIR

BFN

BFN

BFN

BFN

Op

tica

lRo

uti

ng

Sw

itch

Control

(*) EDA project in partnership with BAE Systems, SAAB


Morse Key features

Antenna architecture must enable dynamical reassign of portions of antenna aperture while ensuring simultaneous operation of e-m functions


Radar S&T

ESM

COM 1

ESM

COM 2

COM 3 COM 4

1

3

Hi - Resol.

ESM

2

Example of 3 possible antenna apertures


Morse Key featuresAlternative approaches to be employed for multiple functions to be implemented and

dynamically reassigned will be evaluated:Space Multiplexing by Integrated Optical Switching MatrixesWavelength Division Multiplexing by tunable lasers/ filters, multiwavelength

lasers …


Laser ë3

Laser ë2

WDM

Sub-array i Modulator

WDM Comms

SAR

Detector

Control

Switch

Switch

TTD

Splitter

EDFA Laser ë1

S&T Detector


Architectures for OBFN: Key approaches

Tuneable filtersMultiple lasers + passive

filtersWavelenght Domain Routing

Optical switchesSpace Domain RoutingM-AESA: Routing among Functions

(also digital front end)

Optical Tuneable filtersMultiwavelenght lasers

Changing wavelenght in dispersive media

Optical switchesChanging the physical pathTrue Time Delay Beam

Steering

Critical DevicesTechnical approachFunctionalities


Photonic components for OBFN

Switchable True Time Delay Unit

5 cm 2 cm6 cm

0,7 cm

0,2 cm

Elementary cell of the system

Fiber delays

Integrated delayelements

DOS switch

To subarray

From RFin

5 cm 2 cm6 cm

0,7 cm

0,2 cm

Elementary cell of the system

Fiber delays

Integrated delayelements

DOS switch

To subarray

From RFin

Integrated Optics TTD high speed (10ns) for beam steering

OpticalFibers

OO pp tt iicc aa ll SS ww ii tt cc hh ee ss

Atten.


True Time Delay for fixed beams : Fiber in Boards (BAE)

Photonics components for OBFN

Lower Insertion LossMore Stable operationDOS integrated with time delay waveguide chipMore compact delay moduleMinimum delay increment for 2 Bit Fine TTD: 0.1ps

DrivingElectrode

Dielectricbuffer layer

Adiabatic Y Junction

EO activearea

Digital Optical Switches Reflection TTD


Components for OBFN and routing

Array of 1X4 MagnetoOptical Switchesfor routing matrix in Space Multiplexing(Speed 1 us, Optical Losses 1 dB)

1X8 DOS matrix from Selex SI(Speed 10ns, Optical Losses 7 dB)

WDM mux for WDM based OBFN (Optical Losses 1 dB)


R&D activities in Selex SI

R&D Projects:PNRM 156: Optical Processing of Microwave Signals (2004)EWOCS: Electronic Warfare Optically Controlled Subsystem (2006)MORSE: Multifunction Optical Reconfigurable Scalable Equipment (Running

Project)

Main objectivesTrue Time Delay Optical Beam Forming Networks for Phased Array RadarsOptical Beam Forming and Optical Routing in Multifunction/Multirole AESA

Future PerspectivesImplementation in the routing network of the distribution of LO for RF signal

downconversion in antenna front end Digital MF radar


Conclusion

Optical Beam Forming Networks have a big potential in the application to M-AESA antennas in satellite payloads due to low weight , size EMCcompliance and wide BW

Prototypes of OBFN are based on COTS and on some integrated optics components for improved dynamic range, speed of Beam steering and size, weight

Research funded by Ministry of Defence in this field is going on in the last 10 years for Terrestrial, Naval, Airborne, applications

The achieved solutions are reusable for the Satellite payload antenna and also for future Digital front end Radars

Selex SI is still involved in activity with running project that addresses OBFN and Optical Routing

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